I don't know where would be the best place to post this link. "Slow as molasses in January" is not slang and it is not an idiom. A cliche perhaps? Certainly a metaphor. The article at the link discusses the historical molasses flood in Boston, but, according to the ngram tool, the expression predates that event by several years.http://www.scientificamerican.com/artic ... cs-science

As I said elsewhere, an idiom is more than the sum of its parts. It generally needs to be explained the first time you hear it, or you won't be able to understand it. If you are familiar with the denotation of "slow," "as," "molasses," "in" and "January" (in the northern hemisphere), the meaning of the phrase is obvious. Compare "kick the bucket." If you understand each element, how can it connote "suicide" without additional explanation?

You're right about explanations, whether or not about idioms. Never thought of kick the bucket applying specifically to suicides. It's a generic term for shoving off, passing over, shuffling off this mortal coil, even dying.

But does idiom always require explanation? Slow as molasses is obvious, and to add "in January" is to intensify it. (Just wondered if they substitute July in Brazil?

Enter "idiom" in the search box on the top page of this website and the OneLook Dictionary provides this definition:
"an expression whose meanings cannot be inferred from the meanings of the words that make it up"
It provides the following example: “to have your feet on the ground” is an idiom meaning “to be sensible.”

As for "kick the bucket," the phrase was explained to me by a member of the folk, so I guess I was taken in by a folk etymology.

Living in the South of the USA, January is a pretty temperate month. "Slow as molasses in January" has nothing but an idiomatic meaning to me. We have an English idioms class in our ESL school at church. You can be sure the average Chinese student with a learner's knowledge of English considers this an idiom. Perhaps "kick the bucket" is more idiomatic than the molasses idiom. "Kick the bucket" means die by any means. if you "kick the bucket" you have "bought the farm", "cashed in your chips", are "pushing up daisies". Shakespeare suggests "shuffling off this mortal coil". Passed" or "passed away" are common euphemisms for death that I often hear. I prefer the simple word "died" or "dead".

"I had a dog.
His name was Rover.
And when he died,
He was dead all over.”

Speaking of "kick the bucket," have any of you ever seen the movie "It's a Mad, Mad, Mad, Mad World?" At the beginning, Smiler Grogan (Jimmy Durante) runs over a cliff and is thrown from his car. Four cars of people go over to help him. As he dies, one of his legs straightens out and kicks a bucket down the hill. That's just the start of the madness!

Regards//Larry

"To preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them."
-- Attributed to Richard Henry Lee